The best indication that John Drengenberg has been doing his job well, for 40 years, is that you’ve never heard of him.Most of the things he makes his living worrying about have probably never bothered you, either. You’re not, in all likelihood, terrified of being killed by your TV. You’ve probably realized your child’s Easy Bake is unlikely to burn down your house, and you no doubt pour a cup of coffee without wondering whether the handle will fall off in your hands, spilling six cups of hot coffee all over your crème wool pants.

It is equally unlikely that these things, and thousands of other odd-ball possibilities, will happen, thanks in part to Mr. Drengenberg. He’s spent his career testing almost everything in the average home – from the shingles on the roof to the wiring in walls to the microwave in the kitchen – and making sure it won’t short circuit, blow up, or otherwise injure the American consumer. In what amounts to a chess of mortality, Drengenberg has spent his professional life imagining worst-case scenarios for almost every product on the market, and then trying to avoid them.

“We’ve done such a good job for 114 years, nobody cares. They say, ‘I bought it at Sears. It’s got to be safe. Somebody tested it,’” he says. “We’re the somebody.”

Drengenberg works at Underwriters Laboratories (UL), an independent nonprofit that sets the standards for product safety in America. Its 63 laboratories around the world test and approve almost everything sold in America – every hair dryer, iPod, or length of wiring with a UL seal – with a few exceptions: cars, cosmetics, and food, for example.

Headquartered in Chicago, UL roots here stretch back more than a century, when William Henry Merrill, an electrical engineer from Boston, went to inspect the Palace of Electricity that year at the World’s Fair, along the shores of Lake Michigan. No doubt with the memory of the city’s “great fire” of 1871 heavy on their minds, Chicago’s fire inspection board called Merrill and asked him to find ways of lessening fires that were starting with the new-fangled light bulb. At the palace, hundreds of naked light bulbs were strung on metal wire and nailed to posts with metal nails. “You as modern folk, you would never put a nail through a wire,” says Dengenberg. “But that was rocket science in those days. So fires did start, and the result was UL.”

Today’s UL looks nothing like it would have in Merrill’s day. For starters, even schoolchildren know something specialists then didn’t: Metal conducts electricity with dangerous ease, and rubber insulates it, keeping the current locked into the wires needed to carry it. More than that, though, the exponential growth of consumable goods necessitates more varied testing than 19th century retailers might have imagined. UL’s Chicago campus has a lab for testing washing machines and another for making rain to test outdoor lights. There’s a combustion lab to test ovens – on a recent day, they cooked 200 pizzas, nonstop over eight hours – and a strobe lab, where they test fire alarms for the hearing impaired.

“We’ve got a firing range. We’ve got Magnums, we’ve got rifles, we’ve got 30-calibers, we’ve got all kinds of these things,” Drengenberg adds – not because they test guns, but because they test bulletproof glass. There are atomic absorption spectrometers to test the lead in paint, and thermal gravimetric analysis machines to test the properties of plastic. You couldn’t try this stuff at home.

Every product they test is at the request, and the expense, of its manufacturer, who seeks out UL not because it has to – no federal law mandates safety tests for most items – but because it’s cheaper and easier than a product-injury lawsuit, Drengenberg says. In fact, most retailers won’t stock a product if it hasn’t been safety tested. But it’s all voluntary, a tidy case study of the free market at its best: bottom-line drivers of consumer good.

UL isn’t a monopoly but it is the most well-known of about half a dozen test labs. The UL stamp is both ubiquitous and meaningful enough that, like the cheap electronic goods it’s stamped on, the label is being counterfeited in China.

“There are certain product categories more likely to be counterfeited. They’re the high volume, low cost items,” he says. “Extension cords. Night lights. Power cords.” And, this time of year, Christmas lights. For all products that it tests in China, UL uses a silver holographic label, making it more difficult to copy.

“We have one weapon in the factory.... The UL mark,” says Drengenberg. So UL guards it carefully, through a rigorous documentation process. Every product tested is photographed, all of its parts cataloged, and every test performed described in detail. If it passes, the manufacturer puts it on the assembly line – but at some point during production, a UL inspector will show up, unannounced, for a spot-check, making sure the company is using all the same parts UL saw on the prototype.

“I’ve gone to factories in the Far East and said, ‘Where is the circuit board soldered? I have to measure the temperature of the solder,’ ” Drengenberg remembers. “So they put me in a car, take me down the street, down some alleys, and we enter somebody’s house, and there in the living room is the little solder pot, and a man and a woman are soldering circuit boards.”

Drengenberg started as an intern after college, where he studied circuit engineering. He moved up the testing ranks and today is the global consumer affairs manager. He says he’s a geek, and confesses that a lifetime of setting safety standards can dull a party pretty quickly: “We don’t like balloons. They’re one of the main choking hazards for little children. We’re not a fun group. We don’t like candles, either.”

But sometimes, policing products can be a good time, like when the day is filled by testing TV picture tubes. The tubes only work in a vacuum, which means they’re constantly under thousands of pounds of pressure. Accidentally hit the TV the wrong way, and you might dislodge the tube. UL tests the safety steel that’s supposed to catch a tube in that case.

When it works, “it hits the front piece and harmlessly falls inside the television,” he says, “instead of blasting out the front like a hand grenade.” It’d be a serious injury, but so far he’s never heard of it happening, so Drengenberg indulges a little humor. “We see failures, and they’re such fun. They blow sky high.” From just a standard 12-inch TV? “Yeah – 27 inches is better. More glass.”

UL can’t do anything about products they don’t see, including lead-laden toys from China. Sometimes if they test electric toys, they’ll test for lead in paint. But if the Thomas the Tank Engine set under your Christmas tree isn’t motorized, you probably won’t find a UL stamp on it.

Meeting safety thresholds requires patience and ingenuity. Take the refrigerator-door test. The door is one of the most potentially lethal components of the appliance. UL designed an automated green metal contraption to open and close the door 300,000 times, six times a minute, over several days.

“That’s just the conditioning; that’s not the test,” Drengenberg explains. The lab wants to make sure that, after a fridge has exhausted itself, the door doesn’t get stuck. So, on the 300,001 rotation, “we put a gauge on the door, we pull it open, and if it takes less than 15 pounds of pressure [to open], it passes.... Children still die in old refrigerators because they’re disposed of ... on somebody’s back porch.... It might be a fort, or a sibling will say, ‘Get in there, you’re in jail,’ and they fit.” But, he says, they only have 15 pounds of force in them to kick the door open.

Harder than gaming out disasters and writing standards to prevent them is gauging how well the standards really work. “The fire department can count the number of people that didn’t get hurt. They can say, ‘We carried three people down our ladder,’ ” Drengenberg says. “We don’t know. Last night, there wasn’t a fire in Brooklyn or Chicago, and nobody got killed. But there might have been.”